low-pressure on a Danfoss DHP-M: Class A alarm. The coolant (brine) circuit is the heat pump's low pressure circuit - check the circuit's level; contact a service technician if the alarm reoccurs
Short answer
On a Danfoss heat pump, low-pressure means: Class A alarm. The coolant (brine) circuit is the heat pump's low pressure circuit - check the circuit's level; contact a service technician if the alarm reoccurs. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Class A alarm. The coolant (brine) circuit is the heat pump's low pressure circuit - check the circuit's level; contact a service technician if the alarm reoccurs.
Part involved: low pressure switch.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Manual reset: Press the acknowledge button on the touchscreen (resets all alarms).
What you can check
- Look at the brine expansion tank: the fluid level should be visible (user guide check). Do not refill or open the ground-loop circuit yourself - call the installer. Acknowledge once via the touchscreen; if it persists or recurs, call the installer. If an A-alarm cannot be acknowledged and hot water is needed, the guide allows selecting operating mode 'Auxiliary heater + service'.
What the engineer will check
- Pressure/flow checks on heating or brine side; refrigerant circuit checks.
Who to ask for: heat pump engineer.
Certification: F-Gas category I certificate (refrigerant circuit work).
What you might notice
Sources
- User Guide DHP-M (VUJSD302) ↗ · VUJSD302 · page pp.21-22 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026